This application relates to spinal fusion implants and methods of use thereof.
The spine is a flexible structure that extends from the base of the skull to the tail bone. It contains 33 interconnected bones called vertebrae. Each vertebra is connected to the vertebra above and below at a facet joint. Each vertebra is separated from the vertebra above or below by a cushion-like, fibrocartilage called an intervertebral disc. There are 23 intervertebral discs in the human body: six in the cervical region (i.e. neck); 12 in the thoracic region (i.e. middle back); and five in the lumbar region (i.e. lower back). The human spinal column is configured so that the intervertebral discs act as shock absorbers for the spine. In addition, intervertebral discs act as a ligament that holds vertebrae together. Intervertebral discs also work with the facet joint to allow for slight movement of the spine; together, these structures allow the spine to bend, rotate and, or twist.
The spinal structure can become damaged as a result of degeneration, dysfunction, disease and, or trauma. More specifically, the spine may exhibit disc collapse, abnormal curvature, asymmetrical disc space collapse, abnormal alignment of the vertebrae and, or general deformity. Disc collapse, abnormal curvature, mis-alignment or deformity may lead to imbalance and tilt in the vertebrae. This may result in nerve compression, disability and overall instability and pain. Where a patient suffers from instabilities in the spine that cause pain and, or deformity, surgical intervention may be required.
Currently, surgical treatments to correct spinal deformities, like abnormal curvature and misalignment of the spinal column, involve manipulation of the spinal column by attaching a corrective device, such as rods, wires, hooks or screws, to straighten abnormal curvatures, appropriately align vertebrae of the spinal column and, or reduce further rotation of the spinal column. Interbody implants may be used to correct disc space collapse that results from conditions like Stenosis and Degenerative Disc Disease.
Spinal fusion is often necessary. A fusion is a surgical method wherein two or more vertebrae are joined together (fused) by way of interbody bone grafting to form a single bone. The current standard of care for interbody fusion requires surgical removal of all or a portion of the intervertebral disc. Removal of the intervertebral disc without replacement will likely cause the disc space to collapse; this may lead to further instability of the spine, nerve damage, abnormal joint mechanics and, or pain. Therefore, after removal of the intervertebral disc, a spinal implant is implanted in the interspace. In many cases, the fusion is augmented by a process called fixation. Fixation refers to the placement of screws, rods, plates, or cages to stabilize the vertebrae so that fusion can be achieved.
The traditional surgical course of treatment to correct abnormal curvatures, mis-alignment and, or general spinal deformities is invasive and often requires the dissection of muscle tissue. Such procedures lead to long recovery times, scarring, pain and excess blood loss.
More recently, a minimally invasive surgical fusion technique has been used to correct curvature and deformities of the spine. Under this minimally invasive technique, a lateral approach is taken to reach the spine through small incisions. Through these incisions, discs are removed and an intervertebral spine implant is placed in the intervertebral disc space to restore normal disc height. Fusion follows. A corrective device, such as rods, wires, hooks or screws, is used to stabilize the spine and promote fusion.
Minimally invasive spine surgery offers multiple advantages as compared to open surgery. Advantages include: minimal tissue damage, minimal blood loss, smaller incisions and scars, minimal post-operative discomfort, and relative quick recovery time and return to normal function.